Honing machine



Feb. 20, 1962 B. CRETIN MAITENAZ 3,021,647

HONING MACHINE Filed April 7. 1960 Feb. 20, 1962 cRETlN MAITENAZ 3,021,647

HONING MACHINE 2 Sheets-Sheet 2 Filed April 7, 1960 When it is desired to impart, to parts made of metal or ceramics, a surface finish which is close or equal to an optics standard of polish, it is necessary for the polishing phase to be preceded by a honing operation.

Honing generally consists in rubbing thepart to be worked against another part of complementary shape, and in interposing, between the two, an abrasive agent which, by its abrading action, will progressively bring the part to be Worked to the desired shape. This operating method is commonly used for honing spherical or toroidal surfaces. a

When it is desired to hone other surfaces, it is necessary to resort to different means. As an example, use is made of a flexible honing tool whose surface is locally faced with metal elements, the surface of these elements mating with the surface to be worked. Unfortunately, since the degree of abrasion depends upon the pressure exerted, this method tends todeform the original surface.

In order to overcome this drawback, recourse may be had to a machine such as forms the object of the present invention, by means of which it is possible to obtain a localized honing, area by area, the rate of abrasion being designed so that it shall be uniform at all points on the surface. This result is achieved by the use of a smallsize honing tool which is integral with a spindle capable of imparting to it two separate motions, of which one is a rapid local abrading motion while the other is a slow overall sweeping motion.

In order toexplain the general arrangement adopted in the machine which enables these results to beachieved, reference will be made to the accompanying drawing in which:

FIGURE 1 is a general side view of the machine.

FIGURE 2 is a partial plan view of the moving spindlecarrying parallelogram.

FIGURE 3 is an enlarged view of the lower portion of the spindle and of the abrading-piece.

FIGURE 4is a" possible 'variantfor honing concave surfaces.

Referring now to FIG. 1, the glass A is secured to a mount B which is rotated through the medium of gearwheel C and worm D, a pulley B being keyed to the Worm. On to the glass A is applied an abrading-piece F through the medium of a point G; this point G which is integral with a spindle H mounted for axial rotation in a housing U, is eccentric relative to the axis of the spindle. The spindle H is maintained parallel, at all times, to an oscillating chassis I by means of a pair of connecting-rods J and K which are of equal length and which are articulated respectively on to H and I. The chassis is able to rock to and fro about a horizontal axis which is perpendicular to the plane of the figure and which is designated by an. The mount B is designed to make it possible to bring the mean centre of curvature L of the part to be honed A on to the same level as the rocking axis W. In addition, the length of the point G is adjusted so that I and K shall be substantially horizontal.

The chassis I carries a roller M and is rocked about its shaft 1m by reason of the fact that this roller M bears on a cam N which is slowly rotated by a reduction unit whose input sprocket P is driven by a chain Q. The axis of the spindle H, being at all times parallel to the axis of the chassis 1, passes through the point L, the mean atent centre of curvature of the part A. The cam N is designed so that, having regard for the size and shape of the other moving parts, a sweeping motion of uniform abrading action shall be provided by the part F over the whole of the surface A. The contour of the cam N can be determined by calculation in a first approximation, and can then be modified experimentally by testing on a spherical surface A.

The component elements of the machine must be designed to allow the abrading piece F to sweep the whole of the area A, namely so that the angle 5 formed by the axis of the housing H with the axis of the mount B can reach the maximum value a. The sweeping motion is obtained by the combination of the rotation of the spindle Band hence of the part A--and the rocking motion of the housing H, and hence of the abrading piece F. I

This sweeping motion issupplemented by an abrading motion caused by the rapid rotation of the eccentric driving point G, this rotation being transmitted through the medium of a flexible drive S which connects the spindle -H to a motor R mounted on the chassis I, for example.

In actual fact, the eccentricity of the driving point G is of the order of 1 millimetre, which permits rapid rotations to be obtained about the axis of the spindle H. The abrasive agent, the feeder system forwhich is not shown in FIG. 1, will thus allow'theabrading-piece F to abradeevenly and without anydeformation of the surface A, re-

gardless of whether the latter is metallic or ceramic.

The machine can usefully be completed-by acounterweight Y which is mounted 'for sliding adjustment on a rod forming one piece with the rocking chassis I-. By

suitably setting the position of this counterweight, the pressure exerted by the abrading-piece F on the surfacev of the part to be honed can be adjusted to suit the work to be carried out and in particular the nature of the material from which the part to be honed A and the abrasive used are made.

FIG. 2 shows the various componentelements of the upper moving assembly, including the chassis I and its roller M and the connecting-rods I and K which linkthe housing U to the chassis I. .T he two connecting-rods are generally of monobloc design so as to, ensure a high de gree of rigidity in the whole system. Anfoperating han-. dle T can be provided to allow the entire moving assembly to be raised when changing the glass.-

FIG. 3 shows the abrading-piece on a larger scaleand' in greater detail. In it can be seen the driving point G which is eccentric relative to the axis of the spindle H and the glass A. A pipe W leads in a continuous supply of abrasive agent, while a protective dome V mounted on F prevents the abrasive from penetrating into the stepbearing of the abrading-piece F.

Since this machine is designed to be used primarily for non-spherical surfaces, an abrading-piece of small size, say 16 mm., should be chosen. Naturally, this size is given by way of indication only and it is obvious that, without departing from the scope of the invention, the eccentricity of the driving point G and the size and shape of the abrading-piece F can both be modified.

In FIGS. 1 to 3, the part to be honed A is shown to be of a convex shape. Clearly, the machine can be built to enable concave parts to be honed. FIG. 4 shows the layout of the moving parts for honing a substantially spherical concave surface having a radius of about 80 mm. Taking into account the sizes that would be pracrod K. Conversely, if the radius of said concave part is sufiiciently large, the point L may, in certain cases, be shifted to above the connecting-rod J.

In the interests of simplifying the description given above, the connecting-rods J and K have been assumed to be equal and parallel. A useful variant consists in resorting to an articulated quadrilateral instead of to a regular parallelogram. A choice of unequal lengths for the two pairs of connecting-rods and the difference between the, two opposite sides thus enables a better perpendicularity to be permanently achieved for the spindle H with respect to the nomcircular meridian of the part to be honed.

To allow for non-stopoperation, the layout described hereinabove can be further completed by a bowl X to allow the abrasive agent to be recovered and returned to the pump.

The above description of the machine has been given by way of example only and not in a limiting sense and it is possible, without departing from the scope of the invention, to resort to other arrangements for the various component elements, the object of the invention being solely the combining of a rapid local abrading motion and a sweeping motion, these two motions together ensuring uniform abrasion over the whole of the surface. Thus it would be possible for a vibratory motion to be imparted to the driving point G instead of the circular motion referred' to.

What I claim is:

l. A machine for honing a surface of a work piece, which comprises a stand, a mount for said work piece rotatably supported in said stand for rotation about a vertical axis, means for continuously rotating said mount, a frame mounted on said stand for oscillation about a horizontal axis offset laterally from the axis of rotation of said mount a bearing member above said mount, a rotary spindle rotatable in said bearing member and having on its lower end a driving point eccentric of said spindle, a honing member havingan axial hole engaging said driving point whereby rotation of said spindle produces orbital movement of said honing member, two pairs of vertically spaced parallel links each pivotally connected at one end to said frame and at the other end to said bearing memberwhereby oscillation of said frame about its axis produces oscillatory movement of said bearing member, said links being substantially horizontal and having a length greater than the distance between the axis of oscillation of said frame and its pivotal connections of the uppermostpair of said links, a motor mounted on said frame, flexible means connecting said motor with said spindle to drive said spindle, a cam rotatably supported by said frame for rotation about an axis parallel to said axis of oscillation of said frame, means for rotating said cam, an arm fixed on said frame, and a cam follower carried by said arm and engaging said cam, whereby rotation of said cam produces oscillation of said frame together with the members moveable therewith including said motor having a center of gravity offset from a vertical plane passing through said axis of oscillation in a direction to maintain said cam follower in engagement with said cam by gravity.

2. A machine for honing a surface of a work piece, which comprises a stand, a rotatable mount for said work piece supported by said stand for rotation about a vertical axis, means for continuously rotating said mount, a frame mounted on said stand for oscillation about a horizontal axis offset laterally from the axis of rotation of said mount, a spindle rotatable in said bearing member and having on its lower end a driving point eccentric of said spindle, a honing member having an axial hole engaging said driving point whereby rotation of said spindle produces orbital movement of said honing member, two pairs of vertically spaced parallel links each pivotally connected at one end to said frame and at the other end to said bearing member whereby oscillation of said frame produces oscillatory movement of said bearing member, said links being substantially horizontal and shorter than said frame, a motor mounted on said frame with its axis approximately parallel to said frame and having a shaft, a flexible cable connecting said shaft with said spindle to drive said spindle, a cam rotatable support on said frame, means including speed reducing means for rotating said earn, an arm fixed on said frame, a cam follower carried by said arm and engaging said cam whereby rotation of said cam produces oscillation of said frame, and a variable counterweight biasing said frame in a direction to maintain said cam follower continuously in engagement with said cam.

References Cited in the file of this patent UNITED STATES PATENTS,

1,639,012 Tillyer Aug. 16, 1927 2,087,514 Hubbell July 20, 1937 2,352,146 Desenberg June 20, 1944 2,392,478 Holman Jan. 8, 1946 2,715,803 Bronson Aug. 23, 1955 2,880,555 Brueckner Apr. 7, 1959 FOREIGN PATENTS 377,701 Italy June 3, 1940 

